WATCH: Gatland NOT happy with TMO call
Anscombe, under pressure from Anthony Watson, was deemed to have not grounded the ball cleanly in the 23rd minute of the Six Nations showdown on Saturday.
Two Jonny May tries, the second converted by Owen Farrell, secured a second victory of the tournament for England, who are aiming to secure an unprecedented third successive championship success.
Gatland, though, was left frustrated by the interpretation of the television match official.
“[I] still don’t understand why that wasn’t a try to Gareth Anscombe,” he said in his post-match reaction.
“I think the wording was something about not… grounding, but you can clearly see he gets his hand there first and it’s grounded. [It was a] big game in front of 80,000 to get the decision wrong.
“It was tough, particularly in the conditions, [which] made it difficult for us to move the ball, but I’m proud of us.”
Gatland’s England counterpart Eddie Jones offered a diplomatic response when questioned on the contentious incident.
“I don’t get into that, that’s why we have a TMO up there, he’s got all the time in the world to make the right decision,” he said.
“It was a proper Test match, a real arm wrestle, we’re getting good at winning those sort of games. They’re a tough team, full credit to Wales.”
Asked if he felt England tired toward the end of the contest, Jones said: “Well, they [Wales] had a seven-day turnaround, we had a short turnaround, I’m so proud of our boys.”